Ignition distrubutor structure



Dec. 31, 1968 J. J. STEINKE 3,419,689

IGNITION DISTRIBUTOR STRUCTURE Filed May 1, 1967 INVENTOR United StatesPatent "ice 3,419,689 IGNITION DISTRUBUTOR STRUCTURE John Jacob Steinke,206 Anderson Road, Watchung, NJ. 07060 Filed May 1, 1967, Ser. No.635,184 7 Claims. (Cl. 200-19) ABSTRACT OF THE DISCLOSURE A motorvehicle ignition distributor having a pivot pin and a pair of spacedlugs located in spaced relationship to a rotatable cam mounted in saiddistributor, a rotatable breaker arm pivotally mounted on the pivot pinand bearing against the cam, through a rubbing block fixedly mounted onarm, the arm having a contact fixedly attached; a spring bearing againstthe rotatable breaker arm holding it against the rotating cam; a fixedspring contact assembly fixedly attached to one of the spaced lugs andelectrically insulated therefrom, consisting of a spring steel elementcarrying an electrical contact point, the spring steel element beingincreasingly tensioned by the rotatable breaker arm during the contactphase and resting against an insulated stop in the return position.

This invention relates to ignition distributor structures and isparticularly concerned with an improved breaker point assembly for anignition distributor as used with ignition systems of internalcombustion engines.

One of the objects of this invention is to provide a breaker pointassembly for a distributor in an internal combustion engine, whichmaintains nearly constant timing and circuit closure durationirrespective of wear of the component parts.

Another object of this invention is to provide a breaker assembly, whichneeds no adjustment to maintain its operating characteristics during thelife of the assembly.

A further object of this invention is to provide a breaker assembly,which exhibits an increasing closed circuit duration with increase inspeed.

Still another object of this invention is to provide a breaker assembly,which induces a rapid circuit break in a reproducibly constant patternand thereby reduces oxidation of the contact points.

In carrying out the above objects, it is another object of the presentinvention to provide a grounded contact arm, which is actuated through ahardened steel rubbing block by a hardened steel, lubricated, contouredcam, which minimizes wear and change of timing or closed circuitcharacteristics.

Another object of this invention, is to provide a simplified breakermounting assembly, permissible by virtue of the fact that the breakerpoints do not require continued critical adjustment.

Another object of this invention is to provide a contoured, stepped cam,which causes point contact by outward pressure and opens the circuit asthe high point of the cam leaves the rubbing block.

The action of the breaker assembly in this invention is opposite to theaction of conventional assemblies. In conventional assemblies thecontacts open gradually as the cam exerts an outward pressure on therubbing blocks. Therefore the time of circuit break and the duration ofcircuit closure are dependent upon wear of the cam and of the rubbingblock, wear of the distributor shaft bearing and oxidation of thecontact points.

In the present assembly shown herein the contacts open after the rubbingblock leaves the high point of the cam. This is accomplished by inertiaeffects and also by using a stronger spring holding the rotating pointcontact arm 3,419,689 Patented Dec. 31, 1968 against the cam relative tothe spring in the fixed contact arm. The delay in contact point openingand the open circuit time is governed purely by the difference in springtensions and by the contour of the cam.

Another difliculty encountered with conventional assemblies is bouncingof the contact points upon closure unless spring pressure is criticallyadjusted. In the present assembly the contact points close gradually,due to the stop provided for the fixed contact arm, and due to thegradually increasing slope of the cam face in the direction of rotation.

Conventional breaker assemblies require electrical insulating materialsto insulate the breaker arm from the cam and from the point of rotation.These insulating materialsare subject to rapid wear, and hence to changein operating characteristics. In the present assembly the rotating pointarm is grounded, and therefore employs hardened steel for the wearingparts.

Further objects and advantages of the present invention are apparentfrom the following description. Reference is made to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

In the drawing:

FIGURE 1 is a plan view of a distributor showing the breaker pointassembly and the contoured cam according to the present invention.

FIGURE 2 is an exploded view in perspective showing the component partsof the breaker point assembly.

FIGURE 3 is a view along lines 3-3 in FIGURE 2 showing an elevation ofthe breaker mounting plate.

FIGURE 4 is an elevation view of the distributor cam.

In the drawings and in FIGURE 1 particularly, a breaker point assembly24, according to the present invention, is shown installed in adistributor 17 of conventional design.

The breaker point assembly 24 is preferably secured by screw 23 to aplate 18 that is rotatable within the distributor in response to enginevacuum. The breaker point gap is adjustable by rotating breaker assembly24 about pin 3, which pin engages hole in plate 18.

The rotatable plate 18 also supports condenser 16. Plate 18 is rotatedwithin distributor 17 by means of lever 19, which connects to linkagefrom the vacuum diaphragm. Spring washers 25 and 22 hold down plate 18and provide electrical contact with distributor housing.

Stepped cam 21 rotates independently of plate 18 and is advanced inresponse to engine speed by means of a titgntrifugal advance mechanismlocated beneath the plate In FIGURE 2 rotatable breaker arm 1 is pivotedon pin 3, which is fixedly mounted on breaker mounting plate 24.Rotatable breaker arm 1 is actuated from cam 21 through rubbing block 2,and is held down on pin by means of washer 26 and spring clip 27.Breaker arm 1 is electrically grounded by conductor 15 and carriescontact point 4.

The fixed spring breaker arm 5 is secured to breaker mounting plate 24by means of bolt 10 and nut 12. Breaker arm 5, containing contact point6, is electrically insulated from mounting plate :by means of Teflon ornylon insulators 7 and 9. Electrical current is provided to breaker arm5 through conductor 20, as shown in FIGURE 1.

Point arm return spring 8 is also secured to mounting plate 24 by meansof bolt 10 and nut 12. Return spring 8 is grounded to mounting plate 24,but is electrically insulated from breaker arm 5.

Movement of fixed spring breaker arm 5 is restricted by Teflon or nyloninsulator 13, which insulator is connected to mounting plate 24 by meansof nut 14.

In operation, cam 21 rotates clockwise at a speed one half of enginespeed, causing the rotatable breaker arm 1 to close the primary coilcircuit from conductor 20 through bolt 10, to fixed spring contact arm5, to point contacts 6 and 4, to rotatable breaker arm 1, and hence toground through conductor 15. The condenser 16- is placed betweenconductor 20 and ground 15 to minimize point arcing. When the rubbingblock 2 leaves the high point of cam 21 the contact points 6 and 4separate, breaking the circuit, due to the greater spring tension inreturn spring 8 over the spring tension in spring contact arm 5. Whenrotatable breaker arm 1 and rubbing block 2 reach the low point of cam21, the contact points 4 and 6 open and the spring contact arm 5 isrestricted by stop 13. The cycle is repeated for each cylinder in turn.

The performance is equally effective if the primary current is fedthrough the rotatable breaker arm 1 to contacts 4 and 6 through fixedspring contact arm 5 to ground. In this event the rotatable breaker armmust be electrically insulated from pivot pin 3 and from rotor 21, whilethe fixed spring arm 5 is grounded.

FIGURE 3 shows the projection of pin 3 below mounting plate 24, whichpin engages a hole in plate 18. Prior to securing with screw 23,mounting plate 24 may be rotated about pin 3 in order to adjust pointgap in the open position.

FIGURE 4 shows the cam 21 in elevation. The upper portion is cylindricaland slotted for mounting of the distributor rotor. The cam 21 isprovided with lobes equal in number to the engine cylinders. If two setsof point assemblies are employed on the same cam, the number of lobes ishalved. The lobe contour is gradually increased in radius in thedirection of rotation to the high point. The trailing edge of the lobeis relieved to a negative angle or curve, to permit gradual return ofthe moveable contact arm 1 to the low point of the cam.

While embodiments of the present invention as herein disclosedconstitute preferred forms, it shall be understood that other forms maybe adopted.

What is claimed is as follows:

1. A breaker point assembly mounted on the vacuum advance plate in adistributor, comprising; a pivot pin and a pair of spaced lugs locatedin spaced relationship to a rotatable cam mounted in said distributor; arotatable breaker arm pivotally mounted on the pivot pin and bearingagainst the cam, through a rubbing block fixedly mounted on arm, the armhaving a contact point fixedly attached, which is part of the primaryelectrical circuit; a contoured cam with number of lobes equal to thenumber of engine cylinders, the cam causing an alternate opening andclosing of the contact points; a spring bearing against the rotatablebreaker arm holding it against the rotating cam; a fixed spring contactassembly fixedly attached to one of the spaced lugs and electricallyinsulated therefrom, consisting of a spring steel element carrying anelectrical contact point, which forms a part of the electrical circuitmentioned above, the spring steel element being increasingly tensionedby the rotatable breaker arm during the contact phase and restingagainst an insulated stop in the return position, the insulated stopbeing fixedly mounted on the other spaced lug of the breaker assembly;the primary electrical circuit being electrically connected to the fixedcontact assembly and the rotatable breaker arm being grounded to thedistributor body.

2. A breaker point assembly as described in claim 1 adapted to be bodilyinstalled as a unit on the vacuum advance plate of a distributor,comprising; a support plate apertured to receive a fastening means forsecurement to said vacuum advance plate, said support plate having apivot pin and a pair of spaced lugs located in spaced relationship tothe rotatable cam mounted in the distributor, the support plate beingrotatable about the axis of the pivot pin by engagement with a hole inthe vacuum advance plate, serving as a means of adjusting the point 4gap prior to securing the supportplate with the holddown screw.

3. In a breaker point assembly and distributor as described in claim 1,a cam with a stepped contour, which acts against the rubbing block ofthe rotatable breaker arm causing a gradual closure of the point gap,tensioning of the spring steel element of the fixed contact assembly,and sudden opening of the point gap at the step in the cam contour; thestep in the cam being relieved to a negative angle or curve allowing thebreaker arm to return to the low point of cam in a controlled path andhence reducing the impact on the cam.

4. In a breaker point assembly as described in claim 1, a spring holdingthe rotatable point arm against the cam, which spring has a tensiongreater than the tension in the spring steel element of the fixedcontact assembly, causing the point arms to separate immediately thepressure of the cam on the rubbing block of the rotatable contact arm isrelieved.

5. Two breaker point assemblies as described in claim 1, the rotatablecontact arms bearing against a contoured cam with number of lobes onehalf the number of engine cylinders causing an opening and closing ofthe contact points; the primary electrical circuit being electricallyconnected to the fixed contact assemblies, and the rotatable breakerarms being grounded to the distributor body.

6. A breaker point assembly mounted on the vacuum advance plate in adistributor, comprising; a pivot pin and a pair of spaced lugs locatedin spaced relationship to a rotatable cam mounted in said distributor; arotatable breaker arm pivotally mounted on the pivot pin and in sulatedtherefrom, bearing against the cam through a rubbing block fixedlymounted on arm and insulated therefrom, the arm having a contact pointfixedly attached, which is part of the primary electrical circuit; acontoured cam with number of lobes equal to the number of enginecylinders, the cam causing an alternate opening and closing of thecontact points; a spring bearing against the rotatable breaker armholding it against the rotating cam, which spring is electricalinsulated from the distributor body; a fixed contact assembly fixedlyattached to one of the spaced lugs, consisting of a spring steel elementcarrying an electrical contact point, which forms a part of theelectrical circuit mentioned above, the spring steel element beingtensioned by the rotatable breaker arm during the contact phase andresting against a grounded stop in the return position; the primaryelectrical circuit being electrically connected to the rotatable breakerarm and the fixed contact assembly being grounded to the distributorbody.

7. Two breaker point assemblies as described in claim 6, the rotatablecontact arms bearing against a contoured cam, being insulated therefrom,the cam having one half the number of lobes as engine cylinders andcausing the opening and closing of contact points; the primaryelectrical circuit being electrically connected to the rotatable contactarms and the fixed spring contact assemblies being grounded.

References Cited UNITED STATES PATENTS 1,255,846' 2/1916 Appel 200-302,133,413 10/1938 Arthur 200-19 2,938,085 5/1960 Andrews 200-27 FOREIGNPATENTS 765,242 1/1957 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistanlt Examiner.

U.S. Cl. X.R. 200-27

